GSoC 2020: Add Disney Animation's SeExpr as a new Fill Layer type (master branch)

This MR condenses all changes made in !380 (merged) into the master branch. It includes all changes up to commit 660b0716, plus the necessary adjustments for the new resource system. I have included the load functionality as part of the already commented out blocks of code.

This MR increases the databaseVersion of Krita to 0.0.3, since there is no functionality yet to pick up new resource types.

Test Plan

Load Krita, and add the resource bundle provided at the Krita Artists thread: https://krita-artists.org/t/first-alpha-of-my-gsoc-project-procedural-texture-generator/8127/20 . Now try adding a New Fill Layer of type SeExpr.

Formalities Checklist

• I confirmed this builds.
• I confirmed Krita ran and the relevant functions work.
• I tested the relevant unit tests and can confirm they are not broken. (If not possible, don't hesitate to ask for help!)
• I made sure my commits build individually and have good descriptions as per KDE guidelines.
• I made sure my code conforms to the standards set in the HACKING file.
• I can confirm the code is licensed and attributed appropriately, and that unattributed code is mine, as per KDE Licensing Policy.